Plasma Oxidation/Anodization of Silicon Films for Photovoltaic and Flat Panel Display Applications

由于非晶硅（a- si）或多晶硅（p-Si）薄膜制造的电子器件的各种新应用，最近这些器件的研究获得了动力。例如，目前使用a-Si薄膜生产的实验性太阳能电池的效率超过12%。这些效率使得这种装置对实现大面积、低成本的光伏能源转换系统具有吸引力。另一个例子是a-Si和p-Si薄膜晶体管（tft），它们使制造全彩色平板显示器成为可能。这种显示器可用于笔记本电脑和未来的高清电视。除了平板显示器，用a- Si或p-Si制造的tft可以用作其他大面积电子系统中的开关元件，例如无透镜接触式图像传感器和位置敏感探测器。所有这些器件（平板显示器、图像传感器和位置敏感探测器）都是在低成本的玻璃基板上制造的；因此，制造温度必须保持在600℃以下，以避免玻璃变形。在氢化a-Si器件的情况下，工艺温度应低于450℃，以避免a-Si电子性能的恶化。单晶硅（c-Si）的氧化已成功地应用于集成电路的开发和制造。硅氧化的重要性在于硅的热氧化导致高质量绝缘体和钝化层的生长，其与硅的界面具有相对较少的改变器件性能和影响器件稳定性的表面陷阱。硅集成电路生产中使用的氧化温度在800到1100摄氏度之间，本研究将测试另一种方法，即等离子体氧化或阳极氧化过程，在氧化过程中，生长的薄膜暴露于活性离子、电子、原子氧和紫外线（UV）光子中。这种暴露导致低温下氧化速率的增强。电子回旋共振（ECR）等离子体将用于氧化或阳极氧化a-Si和p-Si薄膜。这些过程的氧化动力学将作为衬底温度和等离子体工艺条件的函数进行研究。将制造电子器件，并将其特性与生长条件相关联。这项技术将影响低成本、高可靠性、平板显示器和太阳能电池的制造

Research on electronic devices fabricated in thin films of amorphous silicon (a-Si) or polycrystalline silicon (p-Si) has recently gained momentum due to a variety of new applications for these devices. For example, the efficiency of experimental solar cells produced using a-Si films currently exceeds 12%. These efficiencies make such devices attractive for the realization of large area, low cost photovoltaic energy conversion systems. Another example is a-Si and p-Si thin film transistors (TFTs) which have made possible the fabrication of full color, flat panel displays. Such displays can be used in laptop computers and in future high definition TV. In addition to flat panel displays, TFTs fabricated in a- Si or p-Si can be used as switching elements in other large area electronic systems such as lenseless contact-type image sensors and position sensitive detectors. All of these devices (flat panel displays, image sensors and position sensitive detectors) are fabricated on low cost glass substrates; therefore the manufacturing temperatures must be kept below 600 C to avoid glass distortion. In the case of hydrogenated a-Si devices, the process temperatures should be below 450 C to avoid deterioration of the electronic properties of the a-Si. Oxidation of single crystal silicon (c-Si) has been used in the successful development and manufacture of integrated circuits. The importance of silicon oxidation is that thermal oxidation of silicon results in the growth of a high quality insulator and passivation layer with an interface to silicon that has relatively few surface traps which alter device properties and affect device stability. Oxidation temperatures used in the production of silicon integrated circuits is in the range of 800 to 1100 C. An alternative method will be tested in this research, the plasma oxidation or anodization process, in which the grown film is exposed to reactive ions, electron, atomic oxygen, and ultra violet (UV) photons during oxidation. This exposure leads to enhancement of the oxidation rates at low temperatures. Electron cyclotron resonance (ECR) plasmas will be used to oxidize or anodize a-Si and p-Si films. The oxidation kinetics of these processes will be studied as functions of the substrate temperature and plasma process conditions. Electronic devices will be fabricated and their characteristics correlated with growth conditions. This technology could impact the manufacture of low cost, high reliability, flat panel displays and solar cells.***//